Robert Comsol wrote:
There are other occasions where McCoy isn't that good with history. Given the choice whether to believe Spock in IS or McCoy in CK, I'd rather listen to Spock.
McCoy would be unlikely to be knowledgeable about Vulcan history, and to be fair Spock seem to get details of Earth history wrong on occasion.
But there is another possibility.
MCCOY: Would you care for a drink, Mister Spock?
SPOCK: My father's "RACE"
was spared the dubious benefits of alcohol.
MCCOY: Now I know why "THEY"
In IS Spock seem to be speaking of the Vulcan people as a whole, the Vulcan species had never been conquered by a external enemy. But the Vulcans had a long history of warfare between themselves, surely there must have been victors and loser in their history. And we've seen with Spock and Tuvok that the Vulcan species has racial sub-divisions.
So when McCoy referred to Spock's father's race
being conquered, maybe he meant just that? A particular race, and not the entire Vulcan species.
Conquered by a different Vulcan race, and not a external enemy.